1. Field of the Invention
This invention relates to track-supported vehicles, such as excavators, and, more particularly, to adjustable idler wheel assemblies for such vehicles.
2. Description of the Prior Art
This invention relates to adjustable idler wheel assemblies used on track-supported vehicles, such as excavators and the like. The typical excavator is supported by a track system which is rigid and provides only a flat support surface. If the terrain over which such vehicles are operated is soft and/or irregular, the effective track length of the vehicle will be reduced, resulting in instability. Such instability may be manifested by the tendency of the vehicle to rock back and forth during digging operations, for example.
The problem has been approached in several ways by earlier track assemblies. One type of prior design, exemplified in U.S. Pat. Nos. 3,447,620 and 3,447,621, includes double or triple walking beam suspensions in which the effective track lengths can be varied by raising one of the track-mounted wheels off the ground by a hydraulic cylinder so as to lower the walking beams and thereby raise the ground clearance of the vehicle.
U.S. Pat. No. 2,860,715 discloses a suspension arrangement in which the track carrier rollers are raised and lowered so as to vary the effective track lengths, thereby increasing the ground clearance of the vehicle.
The off-road, on-road vehicle disclosed in U.S. Pat. No. 3,182,741 includes tandem track-mounted wheels which can be rotated 90.degree. to reduce the effective track lengths for off-road operation of the vehicle.